This Bible contradiction is from the Skeptic's Annotated Bible.
Yes, he was fast asleep.
Judges 4:21 View context
Then Jael Heber's wife took a nail of the tent, and took an hammer in her hand, and went softly unto him, and smote the nail into his temples, and fastened it into the ground: for he was fast asleep and weary. So he died.
No, he was awake and standing up.
Judges 5:26-27 View context
She put her hand to the nail, and her right hand to the workmen's hammer; and with the hammer she smote Sisera, she smote off his head, when she had pierced and stricken through his temples.
At her feet he bowed, he fell, he lay down: at her feet he bowed, he fell: where he bowed, there he fell down dead.